Botulinum toxin type A (Dysport) for preventing chronic migraine

Botulinum toxin type A is being developed to prevent chronic migraine. Chronic migraine is defined as having headache on at least 15 days per month, with at least eight of these instances having features of migraine. Migraine symptoms include nausea (feeling sick), vomiting (being sick), and increased sensitivity to light, sound or smells. In chronic migraine, this would occur for at least three months. It is not fully understood what causes chronic migraine. Some conditions such as depression and anxiety, and triggers such as stress and tiredness, can cause migraines in some people. There is no cure for migraine, and management of chronic migraine is focused on preventive treatment to reduce headache frequency and severity.